The earliest records with small diameter holes were those designed to operate on turntables rotating at 78 r.p.m. The first record changers, i.e., record players which can handle a plurality of records from a stack to provide continuous playing without interruption, of the drop type were similarly characterized. Within relatively recent times, there were developed both the long-playing 331/3 r.p.m. and the small diameter 45 r.p.m. records, the latter, however, being provided with a comparatively large center hole of one and a half inches in diameter, while the former retained the standard small diameter hole.
While a limited number of record players were developed and manufactured specifically and restricted for use with the large diameter hole records, the greatest popular demand was and is for players, and particularly automatic record changers, with narrow diameter spindles to accommodate the standard 78 r.p.m. and the long playing 331/3 r.p.m. large diameter records, especially since the 45 r.p.m. records can also be played thereon by resorting to either special water inserts or by the use of adapters provided by each changer manufacturer. The use of the wafer insert did not meet with popular consumer acceptance because of many factors among which the primary ones were inconvenience and inordinate expense. A further deficiency lies in the poor operation of the record changer with such wafer inserts due to poor and defective structural characteristics, especially after several uses of the wafer-inserted record. As a consequence of the deficiencies of the wafer inserts, and of the generally quite safisfactory performance of the spindle adapters, the latter represent the major marketable product for playing 45 r.p.m. records on automatic record changers.
The earliest adapters were cylindrical in shape and contained the necessary mechanical means to translate the actions of the turntable spindle ejector lever, pusher or equivalent means to actuate the one-by-one drop of records as required. There then followed developments of a flat generally rectangular, adapter with moving parts, both cylindrical and flat adapters with no moving parts and universal adapters, the latter as shown in my earlier U.S. Pat. Nos. 3,300,221 and 3,365,201. Both because of their lower cost and greater reliability due to lack of moving parts which can, obviously, malfunction, the adapter with no moving parts is generally to be preferred. For many of the major record changers, and, in fact, with the majority of those in use and being sold today, there is no adapter available except a flat one with moving parts. The reason for this lies in the basic difference in construction between an adapter with moving parts and one without moving parts. The former type whether cylindrical or rectangular in shape has as its largest and cross-sectional dimension the size of the central opening (actually a bit smaller to permit rotational clearance) of a 45 r.p.m. record, which is 1.5 inches. An adapter with no moving parts has as its general construction an upper portion offset from a lower portion so that the ejector lever of the spindle is exposed and therefore, its largest cross-sectional dimension is about 50% greater than the conventional adapter with moving parts, or in other words, is about 2.25. Because of this difference, and because of the general construction of many, if not the major amount record changers, and particularly because of the construction of the balance (or ballast) arm, the adapter with no moving parts, and more especially, the flat adapter can not be used with these major amounts of changers.
The problem vis-a-vis the balance arm arises from one of the primary functions thereof, which is to maintain the stack of records to be played on the changer in a horizontal position. This is necessary in order to permit the records to drop properly without any jamming or any other difficulty. Another function of the balance arm on many changers is to shut off the record player after the last record is played. This results from the coactions of the tone or playing arm and proper position of the balance arm after the last record has been played.
In order for the balance arm to perform its function of maintaining the record to be played (or stack of records) in a horizontal position, the balance arm must be in the proper position to move freely vertically so as to maintain a force on the record and follow the record stack as records are fed to the playing position on the turntable. With the majority of changers now being manufactured, this "proper position" places the balance arm, generally about one-half inch from the changer spindle. As a consequence of this small clearance, cyclindrical adapters, whether with or without moving parts, cannot be used since the closest that the balance arm can come to the changer spindle is 1/2 the diameter of the cylindrical adapter (1/5inch) minus 1/2 the diameter of the changer spindle (about 0.14 .+-. 0.02 inch) or about 1.34 to 1.38 inches. The prior art flat adapters with moving parts are manufactured so that they are generally rectangular in cross-section with dimensions of about 0.5 inch to 0.8 inch .times. 1.50 inches thereby permitting their use with most, if not all, changers. As pointed out above, however, flat adapters with no moving parts (e.g., rectangular in shape) cannot be used because their larger dimension (i.e., 2.25 inches) resulting from the offset configuration of this type of adapter, interferes with the end portion of the ballast arm. This end portion is generally an arcuate extension of the ballast arm which is necessary to maintain the records or records in the stack in proper horizontal position.
It is, therefore, an object of this invention to provide an adapter with no moving parts which can be used with record changers and particularly with those whose present construction, and especially the construction of the ballast or balance arm, do not normally permit the use of adapters with no moving parts.
It is a further object of this invention to provide a flat adapter, generally of rectangular shape, with no moving parts which can nevertheless be used with most present day record changers.
It is a still further object of this invention to provide a flat adapter with no moving parts which can be used to play 45 r.p.m. large-center hole records on record players provided with a small diameter or narrow spindle.
Other objects will appear thereinafter as the description proceeds.
The objects of the present invention and others are achieved by providing a spindle adapter of the flat or rectangular style and wherein the longitudinal opening or passageway therein, which is adapted to receive the small diameter spindle of the record changer, is provided with means, preferably a recess or groove which is disposed at an acute angle of from about 5.degree. to less than about 45.degree., and preferably from about 10.degree. to about 40.degree. from its normal position (which is a point or small arc) to one on a line which is the locus of points defining the diameter of the narrow spindle of the changer and extending through the mid point of the arc which defines the shelf on said narrow spindle, and which shelf serves to support the bottom record and those, if any on top of this record.
In the prior art, flat adapters with no moving parts, a groove or recess is provided in the narrow spindle passageway for two purposes. One is to provide rearward clearance for a slotted blade and/or record ejector, finger or lever of the narrow spindle. The other purpose is to lock the adapter against rotation relative to the narrow spindle. This is necessary to assure proper alignment of the adaptor with the narrow spindle so that the records will drop properly upon the forward and lateral movement of the ejector lever of the narrow spindle.
A clear disclosure of this can be found in U.S. Pat. No. 3,689,080 to Dennis and particular reference is made to FIG. 9 showing the recess as a "keyhole slot" which is along a line defining the path of movement of the ejector member of the narrow spindle of the record changer. A similar disclosure can also be found in U.S. Pat. No. 3,191,941 to Kahulec wherein a cylindrical non-moving part adapter with such a slot is also shown.